A prior cellular system used a frequency of 2 GHz bands, but a cellular system for next generation mobile communication must use a high frequency of 2-6 GHz bands. As this high frequency has robust straightness, the cellular system for next generation mobile communication have many shadow areas generated by obstacles such as high buildings. Also, as a radio wave of a high frequency band has a large path loss, cell coverage of the cellular system for next generation mobile communication is smaller than that of the prior cellular system. As signal-to-noise ratios (Eb/No) become smaller because of limited power for improved transmission speed of next generation mobile communication, cell coverage becomes increasingly smaller. For solving coverage or data rate, research regarding low-cost relay stations is progressing according to IEEE 802.16j, WINNER project, etc. Introducing these relay stations forms new interference environments which generates interference control problems.
For this interference control problem, adjacent cells in a prior cellular system based on frequency division multiple access (FDMA) or time division multiple access (TDMA) do not use common resource to avoid interference. This resource usage method provides a sufficient signal-to-noise ratio, but has low frequency reuse efficiency.
On the other hand, a prior cellular system based on code division multiple access (CDMA) reduces fluctuation of interference by averaging interference and makes all channels have suitable interference to greatly improve frequency reuse efficiency. However, because of the direction of main service being changed from voice service with a constant data rate to packet service with a variable data rate, the method for improving frequency reuse efficiency through averaging interference is no longer an ideal method. Further, technology with easy interference avoidance such as orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA) is being adapted to the cellular system. However, a method for not only solving interference problems generated by adapting relay stations to the cellular system of OFDM and OFDMA but also maximizing resource usage efficiency has not yet been introduced.